Gas Milage on 85 olds & 90 t-bird (insurance, yellow light, fuel, best)

[steel7]

I have two cars.#1.1985 olds delta 88 royal brougham,4 door,307 v-8 that gets 15 city/20 highway.#2.1990 ford thundebird,2 door,v-6,3.8 that gets 14 city/20 highway.Both cars are fine tuned & run good.I expected the v-6 t-bird to get better gas milage plus its a smaller car.Can anyone tell me why the mpg is pretty much the same on both cars yet the olds is a boat & a v-8 (small block/307) ? Whats the length & total weight of a 85 olds delta 88 & a 90 t-bird ? Both cars have tranny OD & are loaded (tbird has more options).

[seamusnh]

According to EPA ratings, http://www.fueleconomy.gov/***/findacar.htm (broken link), the 90 T bird estimate is 17 city and 24 highway. The 85 Olds estimate is 15 and 20.

The Olds may have a v-8 but the 307 is a "baby v-8" that was introduced by GM mostly to have somehting for the CA market...

[steel7]

Originally Posted by seamusnh

According to EPA ratings, http://www.fueleconomy.gov/***/findacar.htm (broken link), the 90 T bird estimate is 17 city and 24 highway. The 85 Olds estimate is 15 and 20.

The Olds may have a v-8 but the 307 is a "baby v-8" that was introduced by GM mostly to have somehting for the CA market...

My T bird doesnt even get close to 17/24.I have had a tune up,new air & fuel filter,new tires,clean fuel injectors yet i still only get 14/20.The olds is so much more comfortable then the bird but the bird handles better.

[Deez Nuttz]

I do not know off hand how much either car weighs. But I will say having 2 less cylinders doesn't always equal better fuel economy; that the 6 will usually have to work harder than the 8 to push the same amount of weight, and thus usually use more fuel to do so.

I'm also not sure what either engine was rated at fuel economy wise from the factory. Although I kind of believe either engine *should* be getting better mpg than you mentioned.

If nothing else, you could always find a scale and weigh each vehicle. Perhaps the T bird weighs close to the Delta 88 but has a V6 that has to use more fuel to push it?

[solidgold2]

i have an 88 3.8l i would get the same 14-22mpg before i rebuilt the engine and now it gotten worse. Make sure the temperature is at spec. confirm timeing is to spec. other than that driving habit when EPA test the car out is at best conditions for new cars.

[The Continental]

I'd say the tbird probably weighs a good amount less than the olds

[ColdCanadian]

Rolling-resistance is a factor too.
Tire shape, size, compound, alignment can affect it, as well as your wheel bearings, aerodynamic drag etc.
Take your foot off the throttle, coast, and see if the T-bird slows down quicker than the Oldsmobile...

*That's why there are 300-400 hp Corvettes and Camaros from the late 90's or early 2000's can get 30+ mpg highway;
extremely-low drag and rolling resistance.

[M3 Mitch]

Another point is that in 1985, gas economy was a relatively big deal, while in 1990 it was not as much of a priority.

You don't need to be astonished at a V-8 getting better mileage than a V-6, it seems much of the non-enthusiast motoring community is still stuck in 1932 when Ford's V-8 was introduced, it was all about power rather than mileage...

I don't know the weights of these 2 cars, but offhand I don't think one weighs a lot more than the other, probably/maybe the T-bird weighs less but I wouldn't bet on it.

[steel7]

The 90 Tbird weighs 60 lbs less then the 85 olds. I havent driven the Tbird in over 3 months thanks to a careless af fault driver. It just would of cost too much to repair the olds. One thing for sure though is the hartford insurance company is glad they paid out min for my car & bodily injuries. I have a hate now for insurance companies incl my own. The way i got treated by both companies is discusting. If they treated me in person the way i was treated on the phone i would of gone to jail.

[filmsniffer]

I'd pull the codes, even if the pesky yellow light isn't on/flickering...